Colin-Molina Abraham, Jellen Marcus J, García-Quezada Eduardo, Cifuentes-Quintal Miguel Eduardo, Murillo Fernando, Barroso Jorge, Pérez-Estrada Salvador, Toscano Rubén A, Merino Gabriel, Rodríguez-Molina Braulio
Instituto de Química , Universidad Nacional Autónoma de México , Circuito Exterior , Ciudad Universitaria , Ciudad de México , 04510 , Mexico . Email:
Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , USA.
Chem Sci. 2019 Mar 20;10(16):4422-4429. doi: 10.1039/c8sc04398a. eCollection 2019 Apr 28.
Herein we report two crystalline molecular rotors and that show extremely narrow signals in deuterium solid-state NMR spectroscopy. Although this line shape is typically associated with fast-moving molecular components, our VT H NMR experiments, along with X-ray diffraction analyses and periodic DFT computations show that this spectroscopic feature can also be originated from low-frequency intramolecular rotations of the central phenylene with a cone angle of 54.7° that is attained by the cooperative motion of the entire structure that distorts the molecular axis to rotation. In contrast, two isomeric structures ( and ) do not show a noticeable intramolecular rotation, because their crystallographic arrays showed very restricting close contacts. Our findings clearly indicate that the multiple components and phase transitions in crystalline molecular machines can work in concert to achieve the desired motion.
在此，我们报告了两种晶体分子转子，它们在氘固态核磁共振光谱中显示出极窄的信号。尽管这种线形通常与快速移动的分子成分相关，但我们的变温氢核磁共振实验，结合X射线衍射分析和周期性密度泛函理论计算表明，这种光谱特征也可能源于中心亚苯基的低频分子内旋转，其锥角为54.7°，这是通过整个结构的协同运动实现的，该运动使分子轴扭曲以进行旋转。相比之下，两种异构体结构（和）没有显示出明显的分子内旋转，因为它们的晶体排列显示出非常受限的紧密接触。我们的研究结果清楚地表明，晶体分子机器中的多种成分和相变可以协同工作以实现所需的运动。
